1. Field of the Invention
The invention relates in general to a Balun circuit, and more particularly to a Balun circuit manufactured by integrate passive device (IPD) process.
2. Description of the Related Art
Generally speaking, after the antenna of a communication device receives a wireless signal, the antenna will output a single-port signal to a Balun circuit. The Balun circuit will transform the single-port signal to a dual-port signal, and further outputs the dual-port signal to the radio frequency (RF) transceiver for further processing.
Currently, the Balun circuit is manufactured by low temperature co-fired ceramic (LTCC) process. However, the Balun circuit manufactured by the LTCC process must be electrically connected to a substrate through surface-mount technology (SMT) before electrically connecting with the RF transceiver chip disposed on the substrate. As the substrate must reserve the area for the Balun circuit manufactured by the LTCC process and for the RF transceiver chip, the substrate requires a larger area and occupies a larger space in the communication device. Thus, how to reduce the required area for the substrate so as to save the internal space for the communication device has become a focus to the manufacturers.